One of the main reasons marijuana is prescribed in a medical context is that it is an effective treatment for nausea. However, heavy, long-term marijuana use can lead to chronic nausea and vomiting. Known as Cannabinoid Hyperemesis Syndrome, the gag-y stoner equivalent of heartburn confounds researchers. And, thanks to legalization, that confusion is no longer acceptable for healthcare providers.

On Wednesday, emergency room physician Dr. Kennon Heard, who works at the University of Colorado Hospital in Aurora, Colorado, told CBS that he has documented a steady rise in CHS in Colorado since marijuana became widely available.

“It is certainly something that, before legalization, we almost never saw,” Heard said. “Now we are seeing it quite frequently.”

Heard and a team of doctors documented this rise in a 2015 paper published in Academic Emergency Medicine. They studied 120,000 patient visits — half of which were studied in 2008 to 2009 (the “pre-liberalization” period of marijuana) and the other from 2010 to 2011. The doctors found that the prevalence of patients exhibiting cyclical vomiting doubled in that time period.

A man selects marijuana strains to purchase at the 3-D Denver Discrete Dispensary in Denver, Colorado. 

The symptoms associated with CHS are cyclic vomiting, abdominal pain, and nausea. People experiencing CHS typically have a compulsive need to shower — hot water provides temporary and much needed relief. Vomiting periods typically last for 48 hours, but can resume if the patient continues to smoke.

Doctors typically treat patients with CHS with fluid therapy and anti-emetic medications. While it’s theorized that the cannabinoid receptors tetrhydrocannabinol, cannbidiol, and cannabigerol may have an ill effect on the gastrointestinal system, doctors still aren’t sure why CHS happens — right now it’s described as caused by an “unknown mechanism.”

Which is a point of concern for physicians hoping to treat people with CHS. While the illness was first documented in a group of Australians in 2004, and has been steadily documented since then, most cases of CHS go undiagnosed because, as Heard writes, “the relatively low prevalence of this syndrome, and the social stigma regarding marijuana use that discourages self-reporting.” A lack of diagnoses means a even more difficult time determining what exactly causes CHS in the first place.

“They’ll often present to the emergency department three, four, five different times before we can sort this out,” Heard says of patients who come to the hospital with CHS symptoms.

And Heard theorizes that as marijuana becomes increasingly legalized more and more people will come to the hospital not understanding why they’re vomiting.

Photos via Getty Images / Theo Stroomer, Giphy